But even today, even in north America, they're barely rational. Most people don't mentally add up the purchase price plus insurance plus gas plus maintenance etc. And the inconvenience of garage and parking and clearing driveway and snow etc etc.

The reason we have them is convenience. Public transit in North America with our huge suburbs is on average crap.

I firmly believe that for modern generation, car is increasingly a liability not pleasure. So if we / they can exchange it for a self riding car that magically shows up when needed but also magically buggers off when not, we / they will.